How to check if starter is weak

   / How to check if starter is weak #1  

Frank Sorbello

Gold Member
Joined
Jul 12, 2011
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362
Tractor
Power Trac PT-422
How do you check if your starter is bad or going bad?
My 1999 422 when trying to start with a fully charged battery sounds like a dying walrus. I called Robin Subaru a few weeks back about possibly putting in a bigger starter. The engineer said the engine I have, I am limited to the starter that comes with the engine.

I looked for the bolts to try and remove the starter, however it is so tight in the tub I cant see or feel the bolts.

I talked to Terry at PT yesterday, about changing the brushes in it and he said, it is probably best to replace it if it is bad.
How do I check it?

Thanks
Frank
 
   / How to check if starter is weak #2  
....when trying to start with a fully charged battery sounds like a dying walrus...

I wouldn't assume the starter is bad without checking the battery and the battery cables first. Voltage ("fully charged") means little... with a weak cell, not under load, you can have a battery that is 12.5V, yet drops to 9V as soon as you try to start.

You can buy a hydrometer for about $2, which looks like an eyedropper with colored balls inside. Pull the cap off the battery, use it to suck electrolyte and make sure all the balls in the hydrometer float in each cell. The last time I was unable to start my PT422 was because the battery had a dead cell (only 1 of 4 balls floated in one cell). The unloaded voltage of the battery was 12.5V, yet it would drop to less then 9V as soon as I tried to start.

Another thing to look at is clean the battery cables going between the (+) terminal and the solenoid. Then use a piece of wire to jumper out your ignition switch to cause the starter solenoid to spin the engine. Common source of failure is dirty spade connections on your ignition switch, or an ignition switch that has arced internally and now doesn't allow enough current through to kick over the solenoid. Running a jumper wire straight from the battery to the solenoid will rule this out as the cause.

Only when I have verified the battery and interconnecting wiring would I suspect the starter or the solenoid. And usually the solenoid is the culprit before the battery.

On the older Robin engines, the solenoid (actually called a magnetic switch in this case) was separate from the starter, so you would only be out $58 instead of $250 if that is the case (assuming brush replacement didn't solve the problem).
 

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   / How to check if starter is weak #3  
Also completely remove the ground cable from the battery. Clean both ends and the frame or engine block where it connects.

What is the voltage on the + cable clamp at the battery and at the starter when it is turning over?
 
   / How to check if starter is weak
  • Thread Starter
#4  
Thanks Tim,
I am on it. Will check everything like you said.

Frank
 
   / How to check if starter is weak
  • Thread Starter
#5  
I noticed earlier the battery post are pretty much under the side of the outside tub. So since I am going to this work I figured I'd better turn the battery around so there is no chance the post touch the outside top of the tub. Took off the muffler. Disconnected battery.

Don't you know there isn't enough clearance to pull this battery out of the tub. I know the engine was rebuilt in the fall and the battery was replaced in August. Please tell me there is an easier way to pull this battery out.

Are the post on your battery facing the center of the tractor or to outside of the tub?

Thanks
Frank

Should have bought new. Should have bought new>
 
   / How to check if starter is weak #6  
I noticed earlier the battery post are pretty much under the side of the outside tub. So since I am going to this work I figured I'd better turn the battery around so there is no chance the post touch the outside top of the tub. Took off the muffler. Disconnected battery.

Don't you know there isn't enough clearance to pull this battery out of the tub. I know the engine was rebuilt in the fall and the battery was replaced in August. Please tell me there is an easier way to pull this battery out.

Are the post on your battery facing the center of the tractor or to outside of the tub?

Thanks
Frank

Should have bought new. Should have bought new>

You can loosen the bolts that hold the motor mount to the tub and then slide the motor a short distance forward. This should give you enough room to pull the battery up and out. This worked for me.
 
   / How to check if starter is weak
  • Thread Starter
#7  
I want to pull the starter and coil without pulling the engine. Was thinking about drilling a couple holes in the tub at the left rear wheel area so that I can get a socket and extension to the bolts holding the starter. Do you think this will worth trying?
 
   / How to check if starter is weak #8  
I used a hole saw to drill access holes in the tub of my PT 425 when I was working on the motor, make sure to put a plug back into the hole you drill or you will forever be removing debri that comes through the new access holes, in addition you should understand that it could weaken the structural integrity of the tub depending on hole size and location , also years ago I purchased a non-contact amp gauge through NAPA that can be used to check amperage draw of the starter and output of you alternator , this will give you an idea of how many amps the starter is pulling and whether or not it is drawing full-load amperage , also check voltage at all connection/terminal points of contact of the battery cables, the voltage should not vary more than .10 of an volt less than what your battery measures, is so bad connection clean and seal (spray-on anti-corrision) check all positive and negative connections
 
   / How to check if starter is weak
  • Thread Starter
#9  
"You can buy a hydrometer for about $2, which looks like an eyedropper with colored balls inside. Pull the cap off the battery, use it to suck electrolyte and make sure all the balls in the hydrometer float in each cell. The last time I was unable to start my PT422 was because the battery had a dead cell (only 1 of 4 balls floated in one cell). The unloaded voltage of the battery was 12.5V, yet it would drop to less then 9V as soon as I tried to start."

bought a hydrometer. It appears two of the cells are low or bad. The battery was purchased new from Auto zone in August of 2012. I ordered an Interstate battery with more cold cranking amps. Hopefully this helps.
 
   / How to check if starter is weak #10  
"You can buy a hydrometer for about $2, which looks like an eyedropper with colored balls inside. Pull the cap off the battery, use it to suck electrolyte and make sure all the balls in the hydrometer float in each cell. The last time I was unable to start my PT422 was because the battery had a dead cell (only 1 of 4 balls floated in one cell). The unloaded voltage of the battery was 12.5V, yet it would drop to less then 9V as soon as I tried to start."

bought a hydrometer. It appears two of the cells are low or bad. The battery was purchased new from Auto zone in August of 2012. I ordered an Interstate battery with more cold cranking amps. Hopefully this helps.
Good catch, hope this helps.
 
 
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